The present invention relates to an optical head for recording data on an optical disk, reproducing the data recorded thereon, or erasing the data therefrom.
According to a conventional optical disk device, an optical pickup for reading a signal comprises a casing accommodating: a semiconductor laser serving as a light source; an optical system for making laser beams parallel with each other; a beam splitter; a beam deflecting mirror; and an objective lens and the like. FIG. 3 is a schematic view showing such a conventional optical pickup. Optical beams emitted by a semiconductor laser 1 are made to be parallel with each other by a collimating lens 2 and incident on a beam splitter 3. The optical beams which have been corrected in astigmatism by the beam splitter 3 are deflected toward an optical disk 6 by a beam deflecting mirror 4, thus being incident on the objective lens 5. The optical beams converged by the objective lens 5 are reflected by the optical disk 6 and return along the same optical path and are reflected by the beam splitter 3, thus being incident on optical detectors 10 and 11. Since the operation of an optical detecting system 12 is known, the detailed description thereof is omitted. Since the optical system of the above-described optical pickup is accommodated in one casing, the optical system does not become dusty or dirty, but the optical pickup is heavy. Consequently, it takes a long time to move the optical pickup with respect to the optical disk, so that high speed access cannot be accomplished.
In a known separable type optical head, namely, in an optical head in which the deflecting mirror 4 and the objective lens 5 move separately from each other, the optical head is light and high speed access is possible while the optical system becomes dusty or dirty because it is substantially exposed to the outside.